Thursday, February 27, 2014

A week ago, computer models were depicting another surge of arctic air descending into the Southeast, followed by a series of storm systems moving out of the Gulf of Mexico and providing the Carolinas with a threat of snow, sleet or freezing rain in the opening week of March.

A lot has changed in the week.

It might be due to climatology. After all, it's almost the start of March, and we're talking about the Southeast. Cold air and snow aren't unheard of in March across the Carolinas, but it's more difficult for such events to happen than in January or February.

And sure enough, the polar outbreak never quite materialized.

Arctic air has poured into the northern part of the United States, adding yet another miserable chapter to what has been a lousy winter north of the Mason-Dixon line. Temperatures are in single digits and the teens across the Midwest and Great Lakes.

But the really cold air has not reached the Carolinas. Certainly, it's chilly today and will be cold again Friday. But highs are in the upper 40s and lower 50s, rather than the 30s. And a warm-up will begin Saturday.

Now, for those storms ...

Three storm systems appear likely for the Carolinas in the next week, although the first -- on Saturday -- might wind up being a minor event. Precipitation could start as a bit of sleet or freezing rain around daybreak Saturday in the Charlotte region, but all indications from the majority of the computer models are that the precipitation totals will be very light.

We'll watch these developments closely on Friday.

The next system appears likely Monday. The computer models are keeping this system north of the Carolinas. That will put the Charlotte region on the warm side of the storm, and it's why the National Weather Service is forecasting highs in the mid and upper 60s Sunday and Monday. Thunderstorms could develop Monday afternoon.

Storm No. 3 is expected Thursday. This system had been exciting the winter weather-lovers in the region, because some of the computer models a few days ago showed a strong high pressure in the northern United States pumping enough cold air into the Carolinas to make precipitation falls as snow, sleet or freezing rain.

Now the trend from the models is to move the high pressure system out of the way. So when the storm system arrives, temperatures likely will be well above freezing by late next week. Translation ... rain.

Forecasters say the storm that affects the Carolinas on Monday will cross the northern United States and bring snow to a vast area of the country, stretching from the Midwest to the East Coast. Heavy snow could fall in places like Chicago, Detroit, Cleveland, Pittsburgh, Philadelphia, New York and Boston.

Monday, February 24, 2014

We've seen the last of the 60s and 70s for this week, but the computer models increasingly indicate that the outbreak of polar air in the northern United States won't make inroads into the Southeast.

Another strong hint from the computer models: Some wet times are ahead for the Carolinas, especially for the first 10 days of March.

A few days ago, some of the models were producing forecasts of bitter cold pushing into the Carolinas, accompanied by a steady stream of storm systems from an activated southern jet stream. That would be the recipe for a Carolinas snowfall in late February or early March, but such talk is fading early this week.

It now appears as if the outbreak of polar air in the Carolinas instead will be a cool down. Rather than the mid 70s of last week, we're looking at upper 50s for highs on Tuesday, upper 40s Wednesday, and then low to mid 50s for Thursday and Friday. Notice the absence of highs in the 30s and low 40s.

A storm system that is expected to affect parts of the Southeast late Tuesday and early Wednesday now looks like a rain-maker for the Charlotte region, although it could produce some light snow in the mountains. Precipitation amounts look light.

The next system would arrive Saturday, and once again, it appears to be weakening.

The computer models also show storm systems next Monday and again later next week. Once again, the more recent computer model runs are indicating milder temperatures and a storm track that is west of us -- keeping the Carolinas in the warmer air on the east side of the low pressure systems. Translation: rain.

Some very cold air will be locked into the northern part of the United States, however, so while winter's grasp might be weakening in the Carolinas, it will remain a tough customer across the upper Midwest, the Great Lakes and even the Mid-Atlantic and Northeast. Some of those storm systems bringing rain to the Carolinas could be big snow-makers if they hug the East Coast.

Thursday, February 20, 2014

A week ago today, life in Charlotte was at a standstill as we dug out from 7-8 inches of snow and some ice.

Today we're enjoying a second straight day of record-setting temperatures. And forecasters are keeping an eye on conditions that could produce severe thunderstorms Friday morning.

The severe weather threat is in the mid-South today, and parts of western Tennessee and northern Alabama and Mississippi could be in for widespread thunderstorm damage later in the afternoon and evening. On Friday, the biggest threat probably will be to our east, over central and eastern North Carolina.

But for four to six hours Friday morning, the Charlotte region will be in the weather bull's-eye as a cold front crosses the area.

Forecasters expect this evening's line of severe storms to weaken as it approaches the mountains in western North Carolina overnight. As the area of showers and storms moves into the central and eastern Carolinas on Friday, with the additional factor of daytime heating, severe weather could break out again.

But even though the storms will cross the western Carolinas during the morning hours, before daytime heating, there will still be a threat.

"The greatest risk from the storms will be caused by wind gusts that can reach 60 mph," said Alex Sosnowski, a meteorologist with Accu-Weather.

Very strong winds will be blowing in the mid levels of the atmosphere. Meteorologists say that any strong showers or storms that form along the front can bring those powerful winds to the surface.

Incidentally, the cold front will bring our heat wave to an end. Charlotte set a record high of 76 degrees Wednesday, and the temperature already had tied the day's record of 75 at 1 p.m., so another record is nearly certain to fall.

But we won't be dropping into the deep freeze, at least not immediately. Behind the front, Charlotte will still get highs in the mid 60s on Friday, Saturday and Sunday.

That "deep freeze" might be in our future, though. Computer models continue to hint at some much colder weather by the end of next week, and there continue to be hints of a possible winter storm somewhere in the Southeast in the time frame of next Thursday to Saturday.

Wednesday, February 19, 2014

One of the nation's leading online survey companies, uSamp, says it surveyed Charlotte-area residents recently for their opinions on winter weather.

I'm not sure if the survey was taken before or after last week's snowy weather, but the results indicate Charlotteans might not be as fond of snow as you'd believe. It's typical to hear local people say they enjoy their occasional experiences with snow, but uSamp's results indicate otherwise.

The company said 50 percent of the respondents in the Charlotte area said they'd rather be on an island somewhere, with sunshine and warm weather, rather than at home. Another 23 percent said they'd rather be touring Europe. Those who liked the snow and wanted to be at home? Just 20 percent.

When asked whether they go to work or stay home when the weather is bad, the survey showed 47 percent of area residents take the day off. Another 20 percent said they conduct business as usual.

A result that surprised me came to the question of how people felt about the way local school systems handle delays and closings. When the Charlotte-Mecklenburg Schools had an early closing in late January, I saw comments from a number of readers who criticized the school system for botching the effort.

CMS said it was very pleased with its response, and according to uSamp, most people agree. A whopping 70 percent of respondents said they were pleased with the way local school systems handle delays and closings.

The question with the least-surprising result was how Charlotte-area residents prepare for a winter storm. The results had 67 percent of people stocking up on food staples before a storm hits. Of those, according to uSamp, 10 percent said beer and wine has to be a part of the survival package.

Monday, February 17, 2014

Mid and late February has marked the start of spring in the Carolinas a few times in recent years, but that doesn't seem likely in 2014.

A winter that has produced frigid temperatures and four days of snowfall last week is not finished. The long-range computer models seem almost unanimous in predicting a return of cold weather -- and possibly stormy conditions -- before the end of the month.

For sure, we're getting a break from winter this week. Temperatures will be near 70 at midweek, and Friday could bring thunderstorms along a cold front.

The models indicate, however, that a strong dome of high pressure will build this weekend over western Canada. At the same time, a trough of low pressure is predicted to develop over the eastern United States. This is the same combination responsible for the cold weather outbreaks we've experienced on a regular basis since early January.

By early next week, the computers send an unmistakable signal -- very cold air will be pouring into the central and eastern United States. Some of the models show near-record temperatures at the end of the month in the East.

It's not clear how long the cold will last. I've read some meteorologists' predictions that the cold will relent around March 5-7, followed by another warming trend. But other forecasters say the cold will continue into March.

So we have agreement on colder air returning. What about storms?

The computer models show a couple of storm threats next week -- the first around Tuesday or Wednesday. Temperatures probably will be above freezing in at least part of the Carolinas for that system, but another system later in the week could have enough cold air available to bring frozen precipitation to some part of the Southeast.

Snowfall update: It snowed last Monday (a trace in the evening), Tuesday (1 inch in the afternoon), Wednesday (4.6 inches) and Thursday (2.8 inches). Some parts of the Charlotte area also got a trace of snow and sleet early Saturday morning.

The total this winter is 9.3 inches at the airport in Charlotte, and that makes it the snowiest winter in a decade, since the 14.5 inches that fell in 2003-04. In that winter, 13.2 inches fell in a late-February storm.

Wednesday, February 12, 2014

The strong winter storm currently battering the Carolinas is carrying a mix of precipitation forms, and each of them carries its own risks.

All three types of winter precipitation -- snow, sleet and freezing rain -- are part of the storm system. And parts of the immediate Charlotte region will see all three forms during the next 18 hours.

It's the amount of the various forms that is still being debated.

First, a quick review of the three forms and their impact:

SNOW ... If the atmosphere is below freezing from tops of the clouds to the ground, the precipitation falls as snow. It remains frozen all the way to the ground.

Snow causes problems on the roads, of course, but it can be plowed or melted with salt. And it has no impact on power lines, unless the snow is very wet and heavy.

SLEET ... If a rather thin layer of milder air (slightly above freezing) builds in the atmosphere, the snow melts into rain about halfway to the ground, then refreezes as the air gets colder again. The precipitation falls as ice pellets, or sleet.

Sleet obviously bounces off everything, so it has no impact on power lines. But it is a real killer for the roads. Sleet has a habit of partially melting when it hits the ground and then quickly freezing again. It creates a crunchy, slippery road surface.

FREEZING RAIN ... If the atmosphere has a large layer of mild air, but a shallow layer near the surface is cold, then the precipitation falls as rain and freezes quickly at the surface. I've seen a lot of ice storms in which roads remain wet. But ice always forms on exposed surfaces like tree limbs and power lines.

The heavy weight of the ice eventually brings down the tree limbs and power lines. And people lose their electricity.

I prefer none of these, actually, but if we have to deal with something, snow is the easiest to cope with. Sleet is nearly impossible to drive in, but freezing rain takes away electricity, heat, lights and cable television.

Typically, ice accumulations of 1/4 inch or more are enough to cause widespread power outages. The Weather Service is predicting that much ice (or more) from the southeast suburbs of Charlotte southward.

Monday, February 10, 2014

A bit of snow is mixing with light rain showers Monday morning in the Carolinas Piedmont, and a weak low pressure system could bring 1 to 2 inches of snow to the Charlotte area Tuesday morning, but the main event will be Wednesday.

We're within the 48-hour time frame for the computer models, and that's a point when the models get fairly accurate. With all the models predicting a major winter storm, I think it's time to put to bed any doubts about what will happen at midweek.

That being said, here are five things to know about the winter storm that will affect the Carolinas on Wednesday:

1. Temperatures will not be as cold this time.

During the other snow event in Charlotte this year, about two weeks ago, meteorologists had no problem forecasting the precipitation type. The atmosphere was cold from top to bottom, so anything that fell was snow. It was an easy forecast to make, at least from the standpoint of precipitation type.

This time, temperatures will be in the low and middle 30s during the day Tuesday, and they creep up near freezing Wednesday during the bigger storm. That means the snow will be heavy and wet, not fluffy. And it increases the chance that a layer of above-freezing temperatures will become established mid levels of the atmosphere -- which means sleet or freezing rain.

It's a tough forecast.

2. The timing has changed.

Early Sunday, we were talking about snow arriving late Monday or early Tuesday, accumulating a few inches, and then returning early Wednesday and ending later in the day.

Now we have a better idea that Tuesday's system will have fairly light precipitation, and it won't start until later in the morning. The big part of the storm will come Wednesday, and the precipitation won't end until sometime fairly early Thursday morning.

On Sunday, I thought today (Monday) would be the last chance to get chores completed before the roads got bad. But now I think many of us will have at least the early part of Tuesday.

3. The second wave is the biggie.

On Sunday, there were some indications (early in the day) that the heavier snowfall totals might come Tuesday, with most of Wednesday's precipitation falling as sleet, freezing rain or rain. Now the consensus is pointing toward Wednesday's storm as the big one. It could carry more than 1 inch of precipitation, about three times that of Tuesday's system.

4. The path (track) of Wednesday's storm is very important.

Two basic facts: Areas near the center of the low pressure system will get the heaviest precipitation. And the colder air is west of the low pressure's center.

If you want heavy snow in Charlotte, you want the low pressure's center to track up the eastern third of North Carolina or even along the coast. If the low's path is closer to Charlotte (say, U.S. 1), that increases the likelihood of sleet and freezing rain in Charlotte. And if the low's path is west of Charlotte, then we get rain. Forget that third alternative -- it won't happen.

But the other alternatives are still viable options. That's why meteorologists are having a tough time deciding how much snow falls, and where.

5. It will be breezy.

This is really bad news for areas that get the freezing rain. The National Weather Service office in Wilmington mentioned the possibility Monday morning that between .5 and .75 of an inch of ice could form on trees and power lines. That would cause widespread, long-lasting power outages.

A lot of places will be closer to the .25-inch ice accumulation, which usually causes scattered outages. Add in the 15 mph northeast breeze, and a quarter-inch of ice could be big trouble.

Friday, February 7, 2014

The computer models continue their consistent forecast of a winter storm next Tuesday and Wednesday for the Charlotte region.

There are still the same questions that make a forecast anything but certain. However, when the models are this consistent (over a period of several days), it's safe to say that something's up. The problem is that we don't know whether it'll be snow, sleet, freezing rain, or rain.

Or it could be all of the four.

While it's still possible that the storm system delivers a heavy snowfall, it appears as if most of the computer model runs (the models update every six hours) persistently portray a situation with sleet and/or freezing rain. But with temperatures very close to freezing, this also could turn into a storm that delivers a bit of sleet and freezing rain before turning to a cold rain.

The big issue remains the strength and position of high pressure to our north. That system is expected to push its way down the East Coast on Monday. If it remains strong enough to pump cold air into the Charlotte region, the low pressure system will bring frozen precipitation when it arrives. If the high pressure system moves off the Northeast coast, then temperatures in the area might recover above freezing.

WCNC-TV chief meteorologist Brad Panovich posted a note on Facebook earlier Friday, warning people not to believe in either extreme -- that a huge snowstorm is coming, or that we're facing an ice storm like that of December 2002. It was great advice, as it's too early to tell.

But there could be weather news in Charlotte next week. We'll keep things updated over the weekend.

Thursday, February 6, 2014

During the height of the arctic outbreak in late January, a few of the computer models were predicting a ice warming trend through the early part of February. But it looks as if Charlotte's groundhog, which saw its shadow Sunday, was on to something.

While the intensity of the cold air does not rival that of January, we'll be cold enough during the next week to be at risk of trouble-making storm systems. And there appears to be no shortage of trouble-makers on the way.

One weak system, responsible for snowfall Thursday from Dallas to near New Orleans, is expected to zip across the Carolinas late tonight.

Another, bigger storm system is forecast sometime around the middle of next week.

Today's little storm, which was expected to be a nuisance-level event, has proved to be a bit more feisty than first expected. It is dumping heavy snow (for an hour or two) in central Louisiana and Mississippi. As that system crosses the Carolinas late Thursday and early Friday, it could trigger some light snow in the mountains.

Don't be surprised to see a little sleet fall late tonight in Charlotte, although the temperatures indicate rain is more likely. Either way, it won't amount to much.

The bigger story is next week. As usual, there are tons of uncertainty over what will happen.

There are two key players -- a cold high pressure system which is expected to build down the East Coast on Monday and Tuesday, centered over the eastern Great Lakes; and a fairly strong storm system that is forecast to move from the Gulf of Mexico to the Carolinas coast. Some of the computer models indicate there also could be a weak storm system over the Great Lakes, and that could play a role in how everything develops.

The two main computer models, the European and the Global, have been consistent over the past day or two in predicting frozen precipitation in the Carolinas, most likely late Tuesday or Wednesday. Some of the model numbers have been ridiculous with their snowfall predictions.

Temperatures will be cold, but they'll be close to freezing. That means the trick will be in predicting what form of precipitation falls in the Charlotte region. Everything is on the board -- rain, freezing rain, sleet and snow. Maybe all four could fall.

If the high pressure system over the Great Lakes begin moving toward or off the East Coast before the storm arrives, our supply of cold air will weaken. That means we'll get rain. If the high pressure stays in place, frozen precipitation is more likely.

Most of the forecasts I've seen have pointed toward sleet and freezing rain. That's not good. Visiting historic sites and seeing how people lived in the early 19th Century is nice. But most of us don't want to live that way. A major ice storm means power outages, which means no heat, TV and computers. If you lived in Charlotte in December 2002, you know how little fun ice storms are.

This is no time to panic. If every storm predicted by the computer models came to pass this winter, we would've had 100 inches of snow in Charlotte. Instead, we've had 1 inch.

About this blog

Steve Lyttle says growing up in northeastern Ohio, with its foot-deep snows and summertime severe thunderstorms, fueled his interest in meteorology. He has written about weather for 10 years at The Observer. Join the discussion about weather trends and weird weather events -- whether local or around the world.